The present invention generally relates to medical apparatus and methods for medical and cosmetic procedures. More specifically, the invention relates to noninvasive apparatus and methods for occluding blood vessels, such as varicose veins.
There are a number of conditions in which there is a need to shut down and halt the circulation through particular blood vessels. Examples of blood vessels in which one may desire to reduce blood circulation include varicose veins, spider veins, hemangiomas, teleagectasias, hemorrhoids and gastric and intestinal bleeders.
Veins are vessels that carry blood back to the heart. There are a series of one-way, leaflet valves spaced throughout human veins. The valves form an integral portion of the skeletal pump which squeezes blood out of the veins whenever muscles contract. When functioning properly, the valves prevent blood from flowing in the retrograde direction (e.g., away from the heart) back into the vein portion upstream of the valve.
A varicose vein is recognized as a vein which has permanently lost its valvular efficiency and, as a result of continuous dilation under pressure, in the course of time, has become elongated and tortuous. Varicose veins occur frequently in the legs.
In many people, particularly women and those predisposed to the condition, the one-way leaflet valves within the leg vein often become dysfunctional and fail to seal completely. Thus, the portion of vein below the dysfunctional valve must support the weight of additional blood from the vein portion above the valve. The extra pressure increases the diameter of the vein, leads to additional valve leakage, visible varicose veins, and possible ulceration thereof.
In severe cases, varicose veins are treated by surgical excision, in which the vein is removed entirely from the body. The vessels to which the vein is joined are sealed, as with ligatures, at each attachment. The varicose vein is then cut and removed through incisions along the length of the vein. This process is documented to be at least a hundred years old.
A more recently developed, though similar technique is accomplished through a series of incisions, for example incisions of about 1–2 millimeters, along the vein. The target vessel (i.e., varicose vein) is then “hooked” with a stripping device and removed.
Rather than removing the vein, surgical repair of a varicose vein may be performed. Ligation or tying of the vein, through a small incision high in the leg vein, may be performed as a means of eliminating the source of pressure that distends the varicose vein. It is also known to apply a silicone band below the dysfunctional valve to cause narrowing of the valve.
Sclerotherapy is a technique that uses hypodermic needles to inject sclerosing agents into varicose veins to elicit clotting and ultimately scarring within veins to achieve venous occlusion. To treat large varicose veins, this technique requires the use of large volumes of, and/or highly caustic sclerosing agents. Such techniques carry risks of causing unintended thrombosis and embolization, among other things.
Noninvasive surgical procedures have also been developed for treating varicose veins. One such procedure utilizes an intense laser or pulsed broadband light source to treat veins between about 0.1 mm to 3 mm in diameter. These techniques are able to prevent the flow of blood through the veins by heating blood within the veins to form stable blood clots.
Noninvasive procedures for treating vascular disorders other than varicose veins have included the use of light to cause coagulation of small veins near the surface of the skin. For example, U.S. Pat. No. 5,405,368 entitled Method and Apparatus for Electromagnetic Treatment, discloses a method using high intensity, broadband incoherent light to noninvasively treat skin disorders. The pulse length of the light is selected to uniformly heat the entire thickness of the vessel as much as possible to achieve coagulation of the blood in the blood vessels. U.S. Pat. No. 5,344,418, entitled Optical System for Treatment of Vascular Lesion, discloses a system using a narrow band arc lamp for radiating light through a lens in contact with the skin, the peak wavelengths of the light being chosen to be absorbed by the blood to cause coagulation of the blood. A cooling mechanism is provided for protecting the skin from overheating.
In both of the above referenced patents, the disorders treated are small veins, i.e. veins of less than 0.5 mm in diameter. The target vessels may comprise port wine stains, telangiectasias, and cherry and spider angiomas. Although these conventional devices were developed for noninvasively treating vein abnormalities by heating, and coagulating blood by using light, it has not been suggested that the disclosed techniques would beneficial in treating larger vessels, such as varicose veins.
Percutaneous procedures have been used for treating varicose veins. U.S. Pat. No. 5,437,664 entitled Apparatus and Method for Venous Ligation, discloses the use of radio frequency power delivered via a device placed through a skin incision to shrink varicose veins. U.S. Pat. No. 6,398,777 entitled Endovascular Laser Device and Treatment of Varicose Veins, discloses the use of laser radiation delivered via an optical fiber placed through a skin incision to close varicose veins. These systems and methods require an incision to be made in the skin of the patient in order to treat the veins, and thus, provide a substantial risk of infection and require a healing period after the procedure.
There is still a need for simple, yet effective systems and methods for treating veins non-invasively without risk of injuring adjacent tissue. The present invention provides such systems and methods, described in detail below.